A normal blood sugar range when fasting (no food for eight or more hours previous to the test) is between 70 and 99 mg/dL, and a normal level two hours after eating is 140 mg/dL or less, states Virginia Mason Medical Center. Sugar levels change throughout the day and will vary depending on food and exercise.
Blood sugar levels that are higher than the normal range indicate that prediabetes or diabetes is present, states WebMD. The fasting blood sugar range for prediabetes is between 100 and 125 mg/dL, with diabetes generally being diagnosed with a fasting blood sugar level of 126 mg/dL or higher. The two hour blood sugar range for prediabetes is between 141 and 200 mg/dL, and diabetes is indicated when levels are higher than 200 mg/dL.
Individuals with prediabetes face an increased risk of developing diabetes within 10 years, as well as increased risk of heart disease and stroke, according to the National Diabetes Information Clearinghouse. Lifestyle changes such as weight loss, consistent exercise and stopping smoking can greatly reduce the risk of developing diabetes, states WebMD. Research as of 2015 shows that reducing body weight by just 5 to10 percent is usually enough to bring blood sugar levels back to the normal range and avoid or significantly delay onset of diabetes.
Normal value ranges differ by laboratory due to the use of different measurements and test specimens, according to MedlinePlus.